Pressure sensors measure pressure, typically of gases or fluids, at a point in the fluid network. Pressure sensors are used in a range of applications including, for example, medical devices and avionics. Such pressure sensors, including oil-filled pressure sensors, are manufactured and tested in the factory to ensure that they meet the mandatory specifications. The performance and/or calibration of pressure sensors must be periodically checked or tested. Unless the pressure sensors are removed and tested ex-situ, performance deterioration can result from long-term drifts, internal leaks, aging effects, standard wear and tear, and the like. Such deterioration can jeopardize overall system performance. This creates an unacceptable risk especially for critical applications in the areas of aviation, naval, automotive, medical, and the like.
Note that oil-filled sensors rely on the fact that oil is incompressible. The sensor works since the external pressure tries or attempts to move the ultra thin compliant diaphragm but the incompressible internal oil pressure increases until it matches the external pressure. Once the pressures on both sides of the diaphragm are equal there is no force compelling it to move. Any movement of the diaphragm is extremely small.
Currently, in order to verify that the pressure sensors perform within specification, the pressure sensor has to be disengaged or removed from the corresponding system for tests employing a calibrated pressure source. This form of maintenance involves disruption in service and requires costly manual labor.
Therefore, there is a need in the art for providing a pressure sensor with built-in capabilities that can perform in-situ performance testing and self-calibration. There is a further need for a pressure sensor having an internal simulated pressure generator as a built-in pressure source. Such an internal simulated pressure generator is especially suitable for use as a built-in pressure source for oil-filled pressure sensors.